1. Field of the Invention
The disclosure relates generally to methods for start-up lens, and, more particularly to methods for improving start-up fluency of a lens.
2. Description of the Related Art
FIGS. 1, 2 and 3 show a lens 10 and a control system 20. The lens 10 can move along an axis L1. The control system 20 controls the lengthening and shortening of the lens 10.
The lens 10 comprises a base 1, a guided tube 2 telescoped to the base 1, an inner tube 3 inside the guided tube 2, a lens chamber unit 4 inside the inner tube 3, and a drive unit 5 driving the movement of the lens 10. The drive unit 5 comprises a motor 51 set on the base 1.
Referring to FIGS. 1, 2 and 4, when the system starts up, the motor 51 drives the lens 10 from a stowing position H1 to a standby position H2, and a reset point O, a first turning point A, a second turning point B, and a third turning point C are defined in sequence during the movement. During the lengthening of the lens 10, the lens chamber unit 4 progresses in a straight line between the reset point O and the first turning point A, progresses and revolves on its own axis between the first turning point A and the second turning point B, and progresses in a straight line between the second turning point B and the third turning point C.
As shown in FIGS. 2, 3 and 4, the control system 20 comprises a position detection unit 21 coupled to the lens 10, a reset point detection unit 22, a micro-processing unit 23 coupled to the position detection unit 21 and the reset point detection unit 22, and a motor control unit 24 coupled to the micro-processing unit 23 and the motor 51.
If the base 1 senses the lens 10 controlled by the control system 20 to move through the reset point O, a reset point signal is output to the micro-processing unit 23, and the micro-processing unit 23 can determine the position of the reset point O. If the motor 51 continues to rotate, a rotation signal is output to the micro-processing unit 23 for determining the extending position of the lens 10.
During start-up of the system, the micro-processing unit 23 outputs a first signal T1 to the motor control unit 24, and the motor control unit 24 outputs a corresponding first command C1 in response to the first signal T1. The first command C1 rotates the motor 51 with a first angular velocity ω1, driving the guided tube 2 to rotate and leave the base 1. Simultaneously, the inner tube 3 and the lens chamber unit 4 are driven to rotate and leave the base 1, causing the lens 10 to lengthen from the stowing position H1 to the standby position H2.
In the above method, the micro-processing unit 23 outputs the first signal T1 to the motor control unit 24, and the motor control unit 24 outputs the first command C1 corresponding to the first signal T1, where the first command C1 is a fixed voltage rotating the motor 51 at a fixed angular velocity. Conventionally, the lens can be driven to move, but drawbacks result.
First, the lens lengthening is not fluent since the lengthening speed between the first and second turning points A and B is slower than other routes (the reset point O to the first turning point A, and second turning point B to the third turning point C). Second, noises may be generated during the switch of lengthening speeds at the first, second, and third turning points.